/* packet-hsrp.c
 * Routines for the Cisco Hot Standby Router Protocol (HSRP)
 *
 * Heikki Vatiainen <hessu@cs.tut.fi>
 *
 * $Id: packet-hsrp.c 27888 2009-03-29 21:20:15Z etxrab $
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * Copied from packet-vrrp.c
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

/* 
 * RFC 2281 describes opcodes 0 - 2
 *
 * Op Code 3: **** HSRP Interface State Advertisements ****
 * http://www.cisco.com/en/US/products/sw/iosswrel/ps1834/products_feature_guide09186a00800e9763.html
 *
 * An HSRP interface-state advertisement is sent:
 *
 *   * when HSRP on the interface enters or leaves the passive state
 *   * when a group on the interface learns a new Active router
 *   * periodically while the interface is in the passive state
 *
 *                        1                   2                   3
 *    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |   Version     |  Op Code = 3  |           TLV Type            |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |            TLV Length         |      State    |   Reserved    |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |     Active Group Count        |     Passive Group Count       |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |                           Reserved                            |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 *  Passive Group Count:  2 octet
 *
 *     A count of the number of passive groups on the interface.  The range
 *     of values are 0-256.
 *
 *  Active Group Count:  2 octet
 *
 *     A count of the number of active groups on the interface.  The range
 *     of values are 0-256.
 *
 *
 * HSRP Version 2
 *  Ref. http://www.smartnetworks.jp/2006/02/hsrp_8_hsrp_version_2.html (Japanese Only)
 * 
 *  Group State TLV
 *
 *    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |    Type=1     |  Length=40    | HSRP Version  |    Opcode     |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |     State     |   IP Version  |         Group Number          |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |                         Identifier(6octets)                   |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |         Identifier            |       Priority(4octets)       |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |       Priority cont.          |      Hello Time(4octets)      |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |       Hello Time cont.        |      Hold Time(4octets)       |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |       Hold Time cont.         |  Virtual IP Address(16octets) |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |                  Virtual IP Address cont.                     |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |                  Virtual IP Address cont.                     |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |                  Virtual IP Address cont.                     |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |    Virtual IP Address cont.   |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 *  Interface State TLV
 *
 *    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |    Type=2     |    Length=4   |         Active Groups         |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |       Passive Groups          |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 *  Text Authentication TLV
 *
 *    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |    Type=3     |   Length=8    |  Authentication Data(8octets) |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |                   Authentication Data cont.                   |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |   Authentication Data cont.   |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 * MD5 Authentication TLV
 *
 *    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |    Type=4     |    Length     |   Algorithm   |   Padding     |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |             Flags             |      IP Address(4octets)      |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |       IP Address cont.        |         Key ID(4octets)       |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |         Key ID cont.          | Authentication Data(16octets) |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |                   Authentication Data cont.                   |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |                   Authentication Data cont.                   |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |                   Authentication Data cont.                   |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |   Authentication Data cont.   |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <string.h>
#include <glib.h>
#include <epan/packet.h>

static gint proto_hsrp = -1;
static dissector_handle_t data_handle;

static gint hf_hsrp_version = -1;
static gint hf_hsrp_opcode = -1;
/* Opcode 0-2 */
static gint hf_hsrp_state = -1;
static gint hf_hsrp_hellotime = -1;
static gint hf_hsrp_holdtime = -1;
static gint hf_hsrp_priority = -1;
static gint hf_hsrp_group = -1;
static gint hf_hsrp_reserved = -1;
static gint hf_hsrp_auth_data = -1;
static gint hf_hsrp_virt_ip_addr = -1;
/* Advertise (3) */
static gint hf_hsrp_adv_type = -1;
static gint hf_hsrp_adv_length = -1;
static gint hf_hsrp_adv_state = -1;
static gint hf_hsrp_adv_reserved1 = -1;
static gint hf_hsrp_adv_activegrp = -1;
static gint hf_hsrp_adv_passivegrp = -1;
static gint hf_hsrp_adv_reserved2 = -1;

static gint ett_hsrp = -1;

/* HSRPv2 */
static gint hf_hsrp2_version = -1;
static gint hf_hsrp2_opcode = -1;
static gint hf_hsrp2_state = -1;
static gint hf_hsrp2_group_state_tlv = -1;
static gint hf_hsrp2_interface_state_tlv = -1;
static gint hf_hsrp2_text_auth_tlv = -1;
static gint hf_hsrp2_md5_auth_tlv = -1;
static gint hf_hsrp2_ipversion = -1;
static gint hf_hsrp2_hellotime = -1;
static gint hf_hsrp2_holdtime = -1;
static gint hf_hsrp2_priority = -1;
static gint hf_hsrp2_identifier = -1;
static gint hf_hsrp2_group = -1;
static gint hf_hsrp2_virt_ip_addr = -1;
static gint hf_hsrp2_virt_ip_addr_v6 = -1;
static gint hf_hsrp2_auth_data = -1;
static gint hf_hsrp2_active_group = -1;
static gint hf_hsrp2_passive_group = -1;
static gint hf_hsrp2_md5_algorithm = -1;
static gint hf_hsrp2_md5_flags = -1;
static gint hf_hsrp2_md5_ip_address= -1;
static gint hf_hsrp2_md5_key_id= -1;
static gint hf_hsrp2_md5_auth_data= -1;

static gint ett_hsrp2_group_state_tlv = -1;
static gint ett_hsrp2_interface_state_tlv = -1;
static gint ett_hsrp2_text_auth_tlv = -1;
static gint ett_hsrp2_md5_auth_tlv = -1;

#define UDP_PORT_HSRP   1985
#define UDP_PORT_HSRP2_V6   2029
#define HSRP_DST_IP_ADDR "224.0.0.2"
#define HSRP2_DST_IP_ADDR "224.0.0.102"

struct hsrp_packet {          /* Multicast to 224.0.0.2, TTL 1, UDP, port 1985 */
        guint8  version;      /* RFC2281 describes version 0 */
        guint8  opcode;
        guint8  state;
#define HSRP_DEFAULT_HELLOTIME 3
        guint8  hellotime;    /* In seconds */
#define HSRP_DEFAULT_HOLDTIME 10
        guint8  holdtime;     /* In seconds */
        guint8  priority;     /* Higher is stronger, highest IP address tie-breaker */
        guint8  group;        /* Identifies the standby group */
        guint8  reserved;
        guint8  auth_data[8]; /* Clear-text password, recommended default is `cisco' */
        guint32 virt_ip_addr; /* The virtual IP address used by this group */
};

struct hsrpv2_packet {        /* Multicast to 224.0.0.102, TTL 1, UDP, port 1985 */
        guint8  version;
        guint8  opcode;
        guint8  state;
#define HSRP2_DEFAULT_HELLOTIME 3000
        guint32 hellotime;    /* In msecs */
#define HSRP2_DEFAULT_HOLDTIME 10000
        guint32 holdtime;     /* In msecs */
        guint32 priority;     /* Higher is stronger, highest IP address tie-breaker */
        guint16 group;        /* Identifies the standby group */
        guint8  identifier[6]; /* Identifier of sender's MAC address */
        guint8  auth_data[8]; /* Clear-text password, recommended default is `cisco' */
        gchar   virt_ip_addr[16]; /* The virtual IPv4/IPv6 address used by this group */
        guint8  md5_algorithm;  /* MD5 Hash algorithm */
        guint8  md5_flags;      /* Undefined */
        guint8  md5_ip_address; /* IP address of sender interface */
        guint8  md5_key_id;     /* Name of key chain */
        guint8  md5_auth_data[16]; /* MD5 digest data */
};

#define HSRP_OPCODE_HELLO     0
#define HSRP_OPCODE_COUP      1
#define HSRP_OPCODE_RESIGN    2
#define HSRP_OPCODE_ADVERTISE 3
static const value_string hsrp_opcode_vals[] = {
        {HSRP_OPCODE_HELLO,     "Hello"},
        {HSRP_OPCODE_COUP,      "Coup"},
        {HSRP_OPCODE_RESIGN,    "Resign"},
        {HSRP_OPCODE_ADVERTISE, "Advertise"},
	{0, NULL}
};

#define HSRP_STATE_INITIAL  0
#define HSRP_STATE_LEARN    1
#define HSRP_STATE_LISTEN   2
#define HSRP_STATE_SPEAK    4
#define HSRP_STATE_STANDBY  8
#define HSRP_STATE_ACTIVE  16
static const value_string hsrp_state_vals[] = {
        {HSRP_STATE_INITIAL, "Initial"},
        {HSRP_STATE_LEARN,   "Learn"},
        {HSRP_STATE_LISTEN,  "Listen"},
        {HSRP_STATE_SPEAK,   "Speak"},
        {HSRP_STATE_STANDBY, "Standby"},
        {HSRP_STATE_ACTIVE,  "Active"},
	{0, NULL}
};

#define HSRP_ADV_TYPE_INTSTATE 1
#define HSRP_ADV_TYPE_IPREDUN  2
static const value_string hsrp_adv_type_vals[] = {
        {HSRP_ADV_TYPE_INTSTATE, "HSRP interface state"},
        {HSRP_ADV_TYPE_IPREDUN,  "IP redundancy"},
	{0, NULL}
};

#define HSRP_ADV_STATE_DORMANT 1
#define HSRP_ADV_STATE_PASSIVE 2
#define HSRP_ADV_STATE_ACTIVE  3
static const value_string hsrp_adv_state_vals[] = {
        {HSRP_ADV_STATE_DORMANT, "Dormant"},
        {HSRP_ADV_STATE_PASSIVE, "Passive"},
        {HSRP_ADV_STATE_ACTIVE,  "Active"},
	{0, NULL}
};

#define HSRP2_OPCODE_HELLO     0
#define HSRP2_OPCODE_COUP      1
#define HSRP2_OPCODE_RESIGN    2
static const value_string hsrp2_opcode_vals[] = {
        {HSRP2_OPCODE_HELLO,     "Hello"},
        {HSRP2_OPCODE_COUP,      "Coup"},
        {HSRP2_OPCODE_RESIGN,    "Resign"},
	{0, NULL}
};

#define HSRP2_STATE_DISABLED 0
#define HSRP2_STATE_INIT     1
#define HSRP2_STATE_LEARN    2
#define HSRP2_STATE_LISTEN   3
#define HSRP2_STATE_SPEAK    4
#define HSRP2_STATE_STANDBY  5
#define HSRP2_STATE_ACTIVE   6
static const value_string hsrp2_state_vals[] = {
        {HSRP2_STATE_INIT,    "Init"},
        {HSRP2_STATE_LEARN,   "Learn"},
        {HSRP2_STATE_LISTEN,  "Listen"},
        {HSRP2_STATE_SPEAK,   "Speak"},
        {HSRP2_STATE_STANDBY, "Standby"},
        {HSRP2_STATE_ACTIVE,  "Active"},
	{0, NULL}
};

#define HSRP2_IPVERSION_IPV4 4
#define HSRP2_IPVERSION_IPV6 6
static const value_string hsrp2_ipversion_vals[] = {
        {HSRP2_IPVERSION_IPV4, "IPv4"},
        {HSRP2_IPVERSION_IPV6, "IPv6"},
	{0, NULL}
};

#define HSRP2_MD5_ALGORITHM 1
static const value_string hsrp2_md5_algorithm_vals[] = {
        {HSRP2_MD5_ALGORITHM, "MD5"},
	{0, NULL}
};

static int
dissect_hsrp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
	tvbuff_t   *next_tvb;
        gchar dst[16];

	/* Return if this isn't really HSRP traffic
	 * (source and destination port must be UDP_PORT_HSRP on HSRPv1 or HSRPv2(IPv4))
         * (source and destination port must be UDP_PORT_HSRP2_V6 on HSRPv2(IPv6))
         */
	if(pinfo->destport != UDP_PORT_HSRP && pinfo->destport != UDP_PORT_HSRP2_V6)
		return 0;

        /*
         * To check whether this is an HSRPv1 packet or HSRPv2 on dest IPv4 addr.
         */
	address_to_str_buf(&(pinfo->dst), dst, sizeof dst);

        if (pinfo->dst.type == AT_IPv4 && strcmp(dst,HSRP_DST_IP_ADDR) == 0) {
                /* HSRPv1 */
                guint8 opcode, state = 0;

                if (check_col(pinfo->cinfo, COL_PROTOCOL))
                        col_set_str(pinfo->cinfo, COL_PROTOCOL, "HSRP");

                opcode = tvb_get_guint8(tvb, 1);
                if (check_col(pinfo->cinfo, COL_INFO)) {
                        col_add_str(pinfo->cinfo, COL_INFO, 
                                     val_to_str(opcode, hsrp_opcode_vals, "Unknown"));
        	}
        	if (opcode < 3) {
                	state = tvb_get_guint8(tvb, 2);
        		if (check_col(pinfo->cinfo, COL_INFO)) {
                        	col_append_fstr(pinfo->cinfo, COL_INFO, " (state %s)",
                               		     val_to_str(state, hsrp_state_vals, "Unknown"));
        		}
                } else if (opcode == 3) {
                	state = tvb_get_guint8(tvb, 6);
        		if (check_col(pinfo->cinfo, COL_INFO)) {
                        	col_append_fstr(pinfo->cinfo, COL_INFO, " (state %s)",
                               		     val_to_str(state, hsrp_adv_state_vals, "Unknown"));
        		}
        	}

                if (tree) {
                        proto_item *ti;
                        proto_tree *hsrp_tree;
                        gint offset;
                        guint8 hellotime, holdtime;
                        gchar auth_buf[8 + 1];

                        offset = 0;
                        ti = proto_tree_add_item(tree, proto_hsrp, tvb, offset, -1, FALSE);
                        hsrp_tree = proto_item_add_subtree(ti, ett_hsrp);

                        proto_tree_add_item(hsrp_tree, hf_hsrp_version, tvb, offset, 1, FALSE);
                        offset++;
                        proto_tree_add_uint(hsrp_tree, hf_hsrp_opcode, tvb, offset, 1, opcode);
                        offset++;
        		if (opcode < 3) {
        			proto_tree_add_uint(hsrp_tree, hf_hsrp_state, tvb, offset, 1, state);
        			offset++;
        			hellotime = tvb_get_guint8(tvb, offset);
        			proto_tree_add_uint_format(hsrp_tree, hf_hsrp_hellotime, tvb, offset, 1, hellotime,
                                                   "Hellotime: %sDefault (%u)",
                                                   (hellotime == HSRP_DEFAULT_HELLOTIME) ? "" : "Non-",
                                                   hellotime);
        			offset++;
        			holdtime = tvb_get_guint8(tvb, offset);
        			proto_tree_add_uint_format(hsrp_tree, hf_hsrp_holdtime, tvb, offset, 1, holdtime,
                                                   "Holdtime: %sDefault (%u)",
                                                   (holdtime == HSRP_DEFAULT_HOLDTIME) ? "" : "Non-",
                                                   holdtime);
        			offset++;
        			proto_tree_add_item(hsrp_tree, hf_hsrp_priority, tvb, offset, 1, FALSE);
        			offset++;
        			proto_tree_add_item(hsrp_tree, hf_hsrp_group, tvb, offset, 1, FALSE);
        			offset++;
        			proto_tree_add_item(hsrp_tree, hf_hsrp_reserved, tvb, offset, 1, FALSE);
        			offset++;
        			tvb_memcpy(tvb, auth_buf, offset, 8);
        			auth_buf[sizeof auth_buf - 1] = '\0';
        			proto_tree_add_string_format(hsrp_tree, hf_hsrp_auth_data, tvb, offset, 8, auth_buf,
                                                     "Authentication Data: %sDefault (%s)",
                                                     (tvb_strneql(tvb, offset, "cisco", (int)strlen("cisco"))) == 0 ? "" : "Non-",
                                                     auth_buf);
        			offset += 8;
        			proto_tree_add_item(hsrp_tree, hf_hsrp_virt_ip_addr, tvb, offset, 4, FALSE);
        			offset += 4;
        		} else if (opcode == 3) {
        			proto_tree_add_item(hsrp_tree, hf_hsrp_adv_type, tvb, offset, 2, FALSE);
        			offset += 2;
        			proto_tree_add_item(hsrp_tree, hf_hsrp_adv_length, tvb, offset, 2, FALSE);
        			offset += 2;
        			proto_tree_add_item(hsrp_tree, hf_hsrp_adv_state, tvb, offset, 1, FALSE);
        			offset += 1;
        			proto_tree_add_item(hsrp_tree, hf_hsrp_adv_reserved1, tvb, offset, 1, FALSE);
        			offset += 1;
        			proto_tree_add_item(hsrp_tree, hf_hsrp_adv_activegrp, tvb, offset, 2, FALSE);
        			offset += 2;
        			proto_tree_add_item(hsrp_tree, hf_hsrp_adv_passivegrp, tvb, offset, 2, FALSE);
        			offset += 2;
        			proto_tree_add_item(hsrp_tree, hf_hsrp_adv_reserved2, tvb, offset, 4, FALSE);
        			offset += 4;
        		} else {
        			next_tvb = tvb_new_subset(tvb, offset, -1, -1);
        			call_dissector(data_handle, next_tvb, pinfo, hsrp_tree);
        		}
                }
        } else if ((pinfo->dst.type == AT_IPv4 && strcmp(dst,HSRP2_DST_IP_ADDR) == 0) ||
		   (pinfo->dst.type == AT_IPv6 && pinfo->destport == UDP_PORT_HSRP2_V6)) {
                /* HSRPv2 */
                guint offset = 0, offset2;
                proto_item *ti = NULL;
                proto_tree *hsrp_tree = NULL;
                guint8 type,len;

                if (check_col(pinfo->cinfo, COL_PROTOCOL))
                        col_set_str(pinfo->cinfo, COL_PROTOCOL, "HSRPv2");

                if (tree) {
                        ti = proto_tree_add_item(tree, proto_hsrp, tvb, offset, -1, FALSE);
                        hsrp_tree = proto_item_add_subtree(ti, ett_hsrp);
		}

                while (tvb_reported_length_remaining(tvb, offset) > 0) {
                        type = tvb_get_guint8(tvb, offset);
                        len = tvb_get_guint8(tvb, offset+1);

		        offset2 = offset;
                        if (type == 1 && len == 40) {
                                /* Group State TLV */
                                guint8 version,opcode, state = 0, ipver;
                                guint32 hellotime, holdtime;
                                proto_tree *group_state_tlv;

                                if (tree) {
                                        ti = proto_tree_add_uint_format(hsrp_tree, hf_hsrp2_group_state_tlv, tvb, offset, 2, type,
                                        "Group State TLV: Type=%d Len=%d", type, len);
                                }
				offset+=2;

                                version = tvb_get_guint8(tvb, offset);
                                opcode = tvb_get_guint8(tvb, offset+1);
                                if (check_col(pinfo->cinfo, COL_INFO)) {
                                        col_add_fstr(pinfo->cinfo, COL_INFO, "%s",
                                                     val_to_str(opcode, hsrp2_opcode_vals, "Unknown"));
                        	}
				
                                state = tvb_get_guint8(tvb, offset+2);
                        	if (check_col(pinfo->cinfo, COL_INFO)) {
                                       	col_append_fstr(pinfo->cinfo, COL_INFO, " (state %s)",
                                      	             val_to_str(state, hsrp2_state_vals, "Unknown"));
                                }

                                if (tree) {
                                        /* Making Group State TLV subtree. */
                                        group_state_tlv = proto_item_add_subtree(ti, ett_hsrp2_group_state_tlv);
                                        proto_tree_add_item(group_state_tlv, hf_hsrp2_version, tvb, offset, 1, FALSE);
                                        offset++;
                                        proto_tree_add_uint(group_state_tlv, hf_hsrp2_opcode, tvb, offset, 1, opcode);
                                        offset++;
                                        proto_tree_add_uint(group_state_tlv, hf_hsrp2_state, tvb, offset, 1, state);
                			offset++;
                			ipver = tvb_get_guint8(tvb, offset);
                                        proto_tree_add_uint(group_state_tlv, hf_hsrp2_ipversion, tvb, offset, 1, ipver);
                			offset++;
                			proto_tree_add_item(group_state_tlv, hf_hsrp2_group, tvb, offset, 2, FALSE);
                			offset+=2;
                			proto_tree_add_item(group_state_tlv, hf_hsrp2_identifier, tvb, offset, 6, FALSE);
                			offset+=6;
                			proto_tree_add_item(group_state_tlv, hf_hsrp2_priority, tvb, offset, 4, FALSE);
                			offset+=4;

                			hellotime = tvb_get_ntohl(tvb, offset);
                			proto_tree_add_uint_format(group_state_tlv, hf_hsrp2_hellotime, tvb, offset, 4, hellotime,
                                                           "Hellotime: %sDefault (%u)",
                                                           (hellotime == HSRP2_DEFAULT_HELLOTIME) ? "" : "Non-",
                                                           hellotime);
                			offset+=4;
                			holdtime = tvb_get_ntohl(tvb, offset);
                			proto_tree_add_uint_format(group_state_tlv, hf_hsrp2_holdtime, tvb, offset, 4, holdtime,
                                                           "Holdtime: %sDefault (%u)",
                                                           (holdtime == HSRP2_DEFAULT_HOLDTIME) ? "" : "Non-",
                                                           holdtime);
                			offset+=4;
                                        if (ipver == 4) {
                                                /* Fetch Virtual IP as IPv4 */
                                                proto_tree_add_item(group_state_tlv, hf_hsrp2_virt_ip_addr, tvb, offset, 4, FALSE);
                                        } else if (ipver == 6) {
                                                /* Fetch Virtual IP as IPv6 */
                                                proto_tree_add_item(group_state_tlv, hf_hsrp2_virt_ip_addr_v6, tvb, offset, 16, FALSE);
                                        } else {
                                                /* Unknown protocol */
                        			next_tvb = tvb_new_subset(tvb, offset, -1, -1);
                        			call_dissector(data_handle, next_tvb, pinfo, hsrp_tree);
                                                break;
					}
                                        offset+=16;
				}
                        } else if (type == 2 && len == 4) {
                                /* Interface State TLV */
                                guint16 active,passive;
                                active = tvb_get_ntohs(tvb, offset+2);
                                passive = tvb_get_ntohs(tvb, offset+4);
                                
                                if (check_col(pinfo->cinfo, COL_INFO)) {
                                        col_add_fstr(pinfo->cinfo, COL_INFO, "Interface State TLV (Act=%d Pass=%d)",active,passive);
                                }

                                if (tree) {
                                        proto_tree *interface_state_tlv;
                                        ti = proto_tree_add_uint_format(hsrp_tree, hf_hsrp2_interface_state_tlv, tvb, offset, 1, type,
                                        "Interface State TLV: Type=%d Len=%d", type, len);
                                        offset+=2;

                                        /* Making Interface State TLV subtree */
                                        interface_state_tlv = proto_item_add_subtree(ti, ett_hsrp2_interface_state_tlv);
                			proto_tree_add_item(interface_state_tlv, hf_hsrp2_active_group, tvb, offset, 2, FALSE);
                                        offset+=2;
                			proto_tree_add_item(interface_state_tlv, hf_hsrp2_passive_group, tvb, offset, 2, FALSE);
                                        offset+=2;
                                }
                        } else if (type == 3 && len == 8) {
                                /* Text Authentication TLV */
                                if (tree) {
                                        proto_tree *text_auth_tlv;
                                        gchar auth_buf[8 + 1];

                                        ti = proto_tree_add_uint_format(hsrp_tree, hf_hsrp2_text_auth_tlv, tvb, offset, 1, type,
                                        "Text Authentication TLV: Type=%d Len=%d", type, len);
                                        offset+=2;

                                        /* Making Text Authentication TLV subtree */
                                        text_auth_tlv = proto_item_add_subtree(ti, ett_hsrp2_text_auth_tlv);

                			tvb_memcpy(tvb, auth_buf, offset, 8);
                			auth_buf[sizeof auth_buf - 1] = '\0';
                			proto_tree_add_string_format(text_auth_tlv, hf_hsrp2_auth_data, tvb, offset, 8, auth_buf,
                                                             "Authentication Data: %sDefault (%s)",
                                                             (tvb_strneql(tvb, offset, "cisco", (int)strlen("cisco"))) == 0 ? "" : "Non-",
                                                             auth_buf);
                			offset += 8;
                                }
                        } else if (type == 4 && len == 28) {
                                /* Text Authentication TLV */
                                if (tree) {
                                        proto_tree *md5_auth_tlv;

                                        ti = proto_tree_add_uint_format(hsrp_tree, hf_hsrp2_text_auth_tlv, tvb, offset, 1, type,
                                        "MD5 Authentication TLV: Type=%d Len=%d", type, len);
                                        offset+=2;

                                        /* Making MD5 Authentication TLV subtree */
                                        md5_auth_tlv = proto_item_add_subtree(ti, ett_hsrp2_md5_auth_tlv);
                                        proto_tree_add_item(md5_auth_tlv, hf_hsrp2_md5_algorithm, tvb, offset, 1, FALSE);
                                        offset++;
                                        /* Skip padding field */
                                        offset++;
                                        proto_tree_add_item(md5_auth_tlv, hf_hsrp2_md5_flags, tvb, offset, 2, FALSE);
                                        offset+=2;
                                        proto_tree_add_item(md5_auth_tlv, hf_hsrp2_md5_ip_address, tvb, offset, 4, FALSE);
                                        offset+=4;
                                        proto_tree_add_item(md5_auth_tlv, hf_hsrp2_md5_key_id, tvb, offset, 4, FALSE);
                                        offset+=4;
                                        proto_tree_add_item(md5_auth_tlv, hf_hsrp2_md5_auth_data, tvb, offset, 16, FALSE);
                                        offset += 16;
                                }
                        } else {
                                /* Undefined TLV */
				if (tree) {
        				next_tvb = tvb_new_subset(tvb, offset, -1, -1);
        				call_dissector(data_handle, next_tvb, pinfo, hsrp_tree);
				}
                                break;
			}
		        offset = offset2+len+2;
		}
        }

        return tvb_length(tvb);
}

void proto_register_hsrp(void)
{
        static hf_register_info hf[] = {
                { &hf_hsrp_version,
                  { "Version", "hsrp.version",
                    FT_UINT8, BASE_DEC, NULL, 0x0,
                    "The version of the HSRP messages", HFILL }},

                { &hf_hsrp_opcode,
                  { "Op Code", "hsrp.opcode",
                    FT_UINT8, BASE_DEC, VALS(hsrp_opcode_vals), 0x0,
                    "The type of message contained in this packet", HFILL }},

                { &hf_hsrp_state,
                  { "State", "hsrp.state",
                    FT_UINT8, BASE_DEC, VALS(hsrp_state_vals), 0x0,
                    "The current state of the router sending the message", HFILL }},

                { &hf_hsrp_hellotime,
                  { "Hellotime", "hsrp.hellotime",
                    FT_UINT8, BASE_DEC, NULL, 0x0,
                    "The approximate period between the Hello messages that the router sends", HFILL }},

                { &hf_hsrp_holdtime,
                  { "Holdtime", "hsrp.holdtime",
                    FT_UINT8, BASE_DEC, NULL, 0x0,
                    "Time that the current Hello message should be considered valid", HFILL }},

                { &hf_hsrp_priority,
                  { "Priority", "hsrp.priority",
                    FT_UINT8, BASE_DEC, NULL, 0x0,
                    "Used to elect the active and standby routers. Numerically higher priority wins vote", HFILL }},

                { &hf_hsrp_group,
                  { "Group", "hsrp.group",
                    FT_UINT8, BASE_DEC, NULL, 0x0,
                    "This field identifies the standby group", HFILL }},

                { &hf_hsrp_reserved,
                  { "Reserved", "hsrp.reserved",
                    FT_UINT8, BASE_DEC, NULL, 0x0,
                    "Reserved", HFILL }},

                { &hf_hsrp_auth_data,
                  { "Authentication Data", "hsrp.auth_data",
                    FT_STRING, 0, NULL, 0x0,
                    "Contains a clear-text 8 character reused password", HFILL }},

                { &hf_hsrp_virt_ip_addr,
                  { "Virtual IP Address", "hsrp.virt_ip",
                    FT_IPv4, 0, NULL, 0x0,
                    "The virtual IP address used by this group", HFILL }},

		{ &hf_hsrp_adv_type,
		  { "Adv type", "hsrp.adv.tlvtype",
		    FT_UINT16, BASE_DEC, VALS(hsrp_adv_type_vals), 0x0,
		    "Advertisement tlv type", HFILL }},

		{ &hf_hsrp_adv_length,
		  { "Adv length", "hsrp.adv.tlvlength",
		    FT_UINT16, BASE_DEC, NULL, 0x0,
		    "Advertisement tlv length", HFILL }},

		{ &hf_hsrp_adv_state,
		  { "Adv state", "hsrp.adv.state",
		    FT_UINT8, BASE_DEC, VALS(hsrp_adv_state_vals), 0x0,
		    "Advertisement tlv length", HFILL }},

		{ &hf_hsrp_adv_reserved1,
		  { "Adv reserved1", "hsrp.adv.reserved1",
		    FT_UINT8, BASE_DEC, NULL, 0x0,
		    "Advertisement tlv length", HFILL }},

		{ &hf_hsrp_adv_activegrp,
		  { "Adv active groups", "hsrp.adv.activegrp",
		    FT_UINT8, BASE_DEC, NULL, 0x0,
		    "Advertisement active group count", HFILL }},

		{ &hf_hsrp_adv_passivegrp,
		  { "Adv passive groups", "hsrp.adv.passivegrp",
		    FT_UINT8, BASE_DEC, NULL, 0x0,
		    "Advertisement passive group count", HFILL }},

		{ &hf_hsrp_adv_reserved2,
		  { "Adv reserved2", "hsrp.adv.reserved2",
		    FT_UINT32, BASE_DEC, NULL, 0x0,
		    "Advertisement tlv length", HFILL }},

                { &hf_hsrp2_version,
                  { "Version", "hsrp2.version",
                    FT_UINT8, BASE_DEC, NULL, 0x0,
                    "The version of the HSRP messages", HFILL }},

                { &hf_hsrp2_opcode,
                  { "Op Code", "hsrp2.opcode",
                    FT_UINT8, BASE_DEC, VALS(hsrp2_opcode_vals), 0x0,
                    "The type of message contained in this packet", HFILL }},

                { &hf_hsrp2_state,
                  { "State", "hsrp2.state",
                    FT_UINT8, BASE_DEC, VALS(hsrp2_state_vals), 0x0,
                    "The current state of the router sending the message", HFILL }},

                { &hf_hsrp2_group_state_tlv,
                  { "Group State TLV", "hsrp2.group_state_tlv",
                    FT_UINT8, BASE_DEC, NULL, 0x0,
                    "Group State TLV", HFILL }},

                { &hf_hsrp2_interface_state_tlv,
                  { "Interface State TLV", "hsrp2.interface_state_tlv",
                    FT_UINT8, BASE_DEC, NULL, 0x0,
                    "Interface State TLV", HFILL }},

                { &hf_hsrp2_text_auth_tlv,
                  { "Text Authentication TLV", "hsrp2.text_auth_tlv",
                    FT_UINT8, BASE_DEC, NULL, 0x0,
                    "Text Authentication TLV", HFILL }},

                { &hf_hsrp2_md5_auth_tlv,
                  { "MD5 Authentication TLV", "hsrp2.md5_auth_tlv",
                    FT_UINT8, BASE_DEC, NULL, 0x0,
                    "MD5 Authentication TLV", HFILL }},

                { &hf_hsrp2_ipversion,
                  { "IP Ver.", "hsrp2.ipversion",
                    FT_UINT8, BASE_DEC, VALS(hsrp2_ipversion_vals), 0x0,
                    "The IP protocol version used in this hsrp message", HFILL }},

                { &hf_hsrp2_group,
                  { "Group", "hsrp2.group",
                    FT_UINT16, BASE_DEC, NULL, 0x0,
                    "This field identifies the standby group", HFILL }},

                { &hf_hsrp2_identifier,
                  { "Identifier", "hsrp2.identifier",
                    FT_ETHER, BASE_NONE, NULL, 0x0,
                    "BIA value of a sender interafce", HFILL }},

                { &hf_hsrp2_hellotime,
                  { "Hellotime", "hsrp2.hellotime",
                    FT_UINT32, BASE_DEC, NULL, 0x0,
                    "The approximate period between the Hello messages that the router sends", HFILL }},

                { &hf_hsrp2_holdtime,
                  { "Holdtime", "hsrp2.holdtime",
                    FT_UINT32, BASE_DEC, NULL, 0x0,
                    "Time that the current Hello message should be considered valid", HFILL }},

                { &hf_hsrp2_priority,
                  { "Priority", "hsrp2.priority",
                    FT_UINT32, BASE_DEC, NULL, 0x0,
                    "Used to elect the active and standby routers. Numerically higher priority wins vote", HFILL }},

                { &hf_hsrp2_auth_data,
                  { "Authentication Data", "hsrp2.auth_data",
                    FT_STRING, 0, NULL, 0x0,
                    "Contains a clear-text 8 character reused password", HFILL }},

                { &hf_hsrp2_virt_ip_addr,
                  { "Virtual IP Address", "hsrp2.virt_ip",
                    FT_IPv4, 0, NULL, 0x0,
                    "The virtual IP address used by this group", HFILL }},

                { &hf_hsrp2_virt_ip_addr_v6,
                  { "Virtual IPv6 Address", "hsrp2.virt_ip_v6",
                    FT_IPv6, 0, NULL, 0x0,
                    "The virtual IPv6 address used by this group", HFILL }},

                { &hf_hsrp2_active_group,
                  { "Active Groups", "hsrp2.active_groups",
                    FT_UINT16, BASE_DEC, NULL, 0x0,
                    "Active group number which becomes the active router myself", HFILL }},

                { &hf_hsrp2_passive_group,
                  { "Passive Groups", "hsrp2.passive_groups",
                    FT_UINT16, BASE_DEC, NULL, 0x0,
                    "Standby group number which doesn't become the active router myself", HFILL }},

                { &hf_hsrp2_md5_algorithm,
                  { "MD5 Algorithm", "hsrp2._md5_algorithm",
                    FT_UINT8, BASE_DEC, VALS(hsrp2_md5_algorithm_vals), 0x0,
                    "Hash Algorithm used by this group", HFILL }},

                { &hf_hsrp2_md5_flags,
                  { "MD5 Flags", "hsrp2._md5_flags",
                    FT_UINT8, BASE_DEC, NULL, 0x0,
                    "Undefined", HFILL }},

                { &hf_hsrp2_md5_ip_address,
                  { "Sender's IP Address", "hsrp.md5_ip_address",
                    FT_IPv4, 0, NULL, 0x0,
                    "IP Address of the sender interface", HFILL }},

                { &hf_hsrp2_md5_key_id,
                  { "MD5 Key ID", "hsrp2.md5_key_id",
                    FT_UINT32, BASE_DEC, NULL, 0x0,
                    "This field contains Key chain ID", HFILL }},

                { &hf_hsrp2_md5_auth_data,
                  { "MD5 Authentication Data", "hsrp2.md5_auth_data",
                    FT_UINT32, BASE_DEC, NULL, 0x0,
                    "MD5 digest string is contained.", HFILL }}
        };

        static gint *ett[] = {
                &ett_hsrp,
                &ett_hsrp2_group_state_tlv,
                &ett_hsrp2_interface_state_tlv,
                &ett_hsrp2_text_auth_tlv,
                &ett_hsrp2_md5_auth_tlv
        };

        proto_hsrp = proto_register_protocol("Cisco Hot Standby Router Protocol",
	    "HSRP", "hsrp");
        proto_register_field_array(proto_hsrp, hf, array_length(hf));
        proto_register_subtree_array(ett, array_length(ett));

        return;
}

void
proto_reg_handoff_hsrp(void)
{
	dissector_handle_t hsrp_handle;

	data_handle = find_dissector("data");
	hsrp_handle = new_create_dissector_handle(dissect_hsrp, proto_hsrp);
	dissector_add("udp.port", UDP_PORT_HSRP, hsrp_handle);
	dissector_add("udp.port", UDP_PORT_HSRP2_V6, hsrp_handle);
}
